Maspin, a serpin with tumor-suppressing activity in human mammary epithelial cells

MYCN-non-amplified metastatic neuroblastoma with good prognosis and spontaneous regression: a molecular portrait of stage 4S

Stage 4 neuroblastoma (NB) are heterogeneous regarding their clinical presentations and behavior. Indeed infants (stage 4S and non-stage 4S of age <365days at diagnosis) show regression contrasting with progression in children (>365days). Our study aimed at: (i) identifying age-based genomic and gene expression profiles of stage 4 NB supporting this clinical stratification; and (ii) finding a stage 4S NB signature. Differential genome and transcriptome analyses of a learning set of MYCN-non amplified stage 4 NB tumors at diagnosis (n=29 tumors including 12 stage 4S) were performed using 1Mb BAC microarrays and Agilent 22K probes oligo-microarrays. mRNA chips data following filtering yielded informative genes before supervised hierarchical clustering to identify relationship among tumor samples. After confirmation by quantitative RT-PCR, a stage 4S NB's gene cluster was obtained and submitted to a validation set (n=22 tumors). Genomic abnormalities of infant's tumors (whole chromosomes gains or loss) differ radically from that of children (intra-chromosomal rearrangements) but could not discriminate infants with 4S from those without this presentation. In contrast, differential gene expression by looking at both individual genes and whole biological pathways leads to a molecular stage 4S NB portrait which provides new biological clues about this fascinating entity.

Characterisation of tumoral markers correlated with ErbB2 (HER2/Neu) overexpression and metastasis in breast cancer

The receptor tyrosine kinase ErbB2 (HER2/neu) is overexpressed in ˜30% of breast cancers and is associated with poor prognosis and an increased likelihood of metastasis. Clinical treatments such as trastuzumab are effective in less than 35% of women diagnosed as ErbB2-positive, highlighting the necessity of searching for novel targets and alternative therapies. Herein, a proteomic screening strategy combining quantitative-based gel electrophoresis and MS was used to compare the protein expression of 48 normal human breast and tumour tissues differing in ErbB2 expression and lymph node status. The aim was to identify proteins associated with the aggressive phenotype of ErbB2-positive breast cancer which could be potential biomarkers of the disease as well as therapy targets. In total, 177 protein isoforms (107 gene products) differentially expressed between tissue groups were identified. Immunohistochemical staining of a tissue-microarray was used for validation of selected protein candidates. We found that expression of HSP90α, laminin and GSTP1 significantly correlated with ErbB2 expression, while others such as AGR2, NM23H1 and Annexin 2 were overexpressed in greater than 40% of tumours. Finally, knocking-down the expression by RNA interference of three candidates, AGR2, Transgelin2 and NM23H1 resulted in an enhanced invasive capacity of MDA-MB435 cells. These data support the involvement of these targets in tumour progression and identify them as novel biomarkers of the disease.

Serpins in T cell immunity

Serine protease inhibitors (serpins) are a family of proteins that are important in the regulation of several biological processes. This mainly involves the inhibition of serine proteases, although some serpins inhibit a different class of proteases or even function without inhibitory activity. In contrast to other protease inhibitor families, serpins inhibit their target proteases by a specific mechanism, which depends on a change in conformation. This review primarily focuses on one subgroup of serpins--ovalbumin (ov)-serpins. Different than most members of the family, this group of serpins lacks secretion signal sequences and therefore, mainly functions intracellularly. In addition to expression in most normal tissues, ov-serpins can be found in multiple different cells of the immune system. Interestingly, expression of ov-serpins in these cells is tightly regulated, indicating a role for these serpins in the regulation of immune responses. The role of serpins in the immune response will be the topic of this review.

The IkappaB kinase - a bridge between inflammation and cancer

A potential link between inflammation and cancer has been suspected for over a century, but the exact molecular mechanisms connecting the two remained nebulous. We proposed that NF-kappaB transcription factors regulated via the IkappaB kinase (IKK) complex play a critical role in coupling inflammation and cancer and have set out to test this hypothesis in mouse models of cancer. Using mice bearing mutations in the genes coding for the IKKbeta and IKKalpha catalytic subunits we obtained evidence supporting a critical role for IKKbeta in tumor promotion and more recently identified the involvement of IKKalpha in metastatogenesis. Whereas the major pro-tumorigenic function of IKKbeta is mediated via NF-kappaB, the pro-metastatic function of IKKalpha is NF-kappaB-independent. In addition to illustrating the critical roles of the two IKK molecules in linking inflammation and cancer and providing an explanation for increased cancer risk in response to persistent infections and inflammation, these results also identify new targets for development of novel anti-cancer therapies and preventive strategies. Instead of targeting the cancer cell itself, as done by conventional anti-cancer drugs, the new therapeutics will target processes that occur within inflammatory cells that are essential for cancer development and progression. Unlike cancer cells, inflammatory cells retain a normal and stable genome and therefore are unlikely to become genetically resistant to therapeutic intervention.

Doxycycline treatment prevents alveolar destruction in VEGF-deficient mouse lung

In vivo lung-targeted VEGF gene inactivation results in pulmonary cell apoptosis, airspace enlargement, and increased lung compliance consistent with an emphysema-like phenotype. The predominant hypothesis for the cause of lung destruction in emphysema is an imbalance between active lung protease and anti-protease molecules. Therefore, we investigated the role of protease (e.g., matrix metalloproteinases--MMPs) and anti-protease (e.g., tissue inhibitors of metalloproteinases--TIMPs) expression in contributing to the lung structural remodeling observed in pulmonary-VEGF-deficient mice. VEGFLoxP mice instilled through the trachea with an adeno-associated virus expressing Cre recombinase (AAV/Cre) manifest airspace enlargement and a greater (P < 0.05) mean linear intercept (MLI: 44.2 +/- 4.2 microm) compared to mice instilled with a control virus expressing LacZ (31.3 +/- 2.5 microm). Airspace enlargement was prevented by the continuous administration of the general MMP inhibitor, doxycycline (Dox) (Cre + Dox: 32.6 +/- 2.5 microm), and MLI values were not different from either control (LacZ + Dox: 30.5 +/- 1.2 microm). In situ magnetic resonance imaging of VEGF gene inactivated mouse lungs revealed uneven inflation, residual trapped gas volumes upon oxygen absorption deflation/re-inflation, and loss of parenchymal structure; effects that were largely prevented by Dox. Five weeks after AAV/Cre infection Western blot revealed a 9.9-fold increase in pulmonary MMP-3, and 2-fold increases in MMP-9 and TIMP-2. However, the increase in MMP-3 was prevented by Dox administration and was associated with a 2-fold increase in serpin b5 (Maspin) expression. These results suggest that doxycycline treatment largely prevents the aberrant lung remodeling response observed in VEGF-deficient mouse lungs and is associated with changes in protease and anti-protease expression.

IRF6 in development and disease: a mediator of quiescence and differentiation

Post utero development of the mammary gland is a complex developmental process characterized by states of rapid cell proliferation (branching morphogenesis) followed by functional differentiation (lactation) and the consequent apoptosis (involution) of the secretory mammary epithelial cell. This process is cyclical, such that involution returns the mammary gland to a near-virgin-like state capable of responding to morphogenic cues with each consecutive pregnancy. Importantly, many of the regulatory processes which oversee mammary gland development are corrupted or otherwise compromised during the development of breast cancer. For example, Interferon Regulatory Factor 6 (IRF6) is a novel protein with growth inhibitory properties that was initially identified in mammary epithelial cells through its interaction with maspin, a known tumor suppressor in normal breast tissue. Recent findings from our laboratory suggest that IRF6 functions synergistically with maspin to regulate mammary epithelial cell differentiation by acting on the cell cycle. This perspective focuses on the possible involvement of IRF6 in promoting differentiation by regulating exit from the cell cycle and entry into the G(0) phase of cellular quiescence, and how these new findings shed light on normal mammary gland development and the initiation and progression of breast cancer.

Maspin overexpression correlates with increased expression of vascular endothelial growth factors A, C, and D in human ovarian carcinoma

The vascular endothelial growth factor (VEGF) family, including VEGFA, VEGFC, and VEGFD, plays an essential role in the angiogenesis of both pathologic and nonpathologic conditions. Maspin belongs to the serpin superfamily and has been identified as a tumor suppressor because it inhibits motility, invasion, and angiogenesis. Few studies have compared maspin with VEGF in ovarian carcinoma. Therefore, we investigated the expression and correlation of maspin, VEGFA, VEGFC, and VEGFD with the tumorigenesis of the ovary and clinicopathologic variables. Using immunohistochemistry, we examined maspin, VEGFA, VEGFC, and VEGFD expression in 60 ovarian carcinoma tissues (35 serous papillary carcinomas, 18 endometrioid carcinomas, and 7 primary ovarian mucinous carcinomas). Staining of cells was scored as +2 if more than 50% of the cells were positive, as +1 if less than 50% of the cells were positive, and as negative if none of the cells stained positive. Overexpression of maspin, VEGFC, and VEGFD was significantly associated with high tumor grade (P<.001, P=.004, P<.001, respectively), clinical stage (P=.002, .01, and .001, respectively), the presence of ascites (P<.001, P=.03, and P=.001, respectively), and the presence of metastatic lymph nodes (P=.002, P<.001, and P<.001, respectively). Maspin was correlated with VEGFA (P=.01), VEGFC (P<.001), and VEGFD (P<.001). The VEGFA score was positively correlated with high tumor grade (P=.04), lymphovascular space invasion (LVSI) (P<.001), International Federation of Gynecology and Obstetrics (FIGO) stage (P=.009), maspin, VEGFC (P=.003), and VEGFD (P=.003), but it was not correlated with the presence of ascites and metastatic lymph nodes. Maspin, VEGFC, and VEGFD are expressed in ovarian tumors with a poor prognostic parameters, and seem to play a role in ovarian cancer angiogenesis, progression, and lymph node metastases. Our results indicate that in contrast to most other carcinomas, maspin expression is directly associated with the biological aggressiveness of ovarian carcinoma. These results may offer new insights regarding the role of maspin in ovarian cancer and might also affect the diagnosis and treatment strategies.

Role of prolactin and vasoinhibins in the regulation of vascular function in mammary gland

The formation of new blood vessels has become a major focus of mammary gland research stimulated by the therapeutic opportunities of controlling angiogenesis in breast cancer. Normal growth and involution of the mammary gland are profoundly affected by the expansion and regression of blood vessels, whereas dysregulation of angiogenesis is characteristic of breast cancer growth and metastasis. Prolactin stimulates the growth and differentiation of the mammary gland under normal conditions, but its role in breast cancer is controversial. Its action is complicated by the fact that prolactin itself is angiogenic, but proteases cleave prolactin to generate vasoinhibins, a family of peptides that act on endothelial cells to suppress angiogenesis and vasodilation and to promote apoptosis-mediated vascular regression. This review summarizes our current knowledge about the vascular effects of prolactin and the generation and action of vasoinhibins, and discusses their possible contribution to the regulation of blood vessels in the normal and malignant mammary gland.

Maspin and p53 protein expression in gastric adenocarcinoma and its clinical applications

OBJECTIVES

To investigate the role of maspin and p53 expression in the progression of gastric cancer, and its value as a prognostic indicator.

MATERIALS AND METHODS

The expression of maspin and p53 in 152 cases of gastric cancer was detected by immunohistochemistry and compared with the clinicopathologic tumor parameters. The relationship between maspin and p53 expression was also analyzed in the gastric cancers.

RESULTS

The positive expression rates for maspin and p53 in the cancers were 71.7% (109 of 152 cases) and 56.6% (86 of 152 cases), respectively. Two patterns of immunostaining for maspin were seen in the maspin-positive gastric cancer cases: cytoplasm-only staining (67.0%, 73 of 109 cases) and staining of both cytoplasm and nucleus (33.0%, 36 of 109 cases). Maspin expression showed a negative association with histologic grade, depth of invasion, metastasis, and TNM stage (all P<0.05). p53 expression showed an association with node metastasis, and TNM stage (both P<0.05). Maspin expression was negatively correlated with p53 expression (P<0.001, r=-0.291). In univariate log-rank analysis, loss of maspin expression, histologic grade, distant metastasis, and TNM stage were associated with patient survival. Interestingly, patients with nuclear and cytoplasmic maspin expression survived longer than those with only cytoplasmic expression. However, in multivariate analysis TNM stage and regional node metastasis were the only independent prognostic factors.

CONCLUSIONS

Maspin expression might be an important factor in tumor progression and patient prognosis, but is not an independent prognostic factor. Maspin expression is inversely correlated with mutant p53 expression in gastric cancer, which suggests that maspin expression is regulated by the p53 pathway.

Maspin and Mutant p53 expression in malignant melanoma and carcinoma: use of tissue microarray

Maspin (mammary serine protease inhibitor), a member of the serpin family, has been shown to inhibit angiogenesis, tumor invasion, and metastasis. Previous studies suggest a p53-dependent regulatory pathway of maspin protein expression. Its loss correlates with progression of disease in both breast and prostate cancer. We studied the in vivo correlation of maspin expression with p53 mutation in malignant melanoma (MM) with and without use of tissue microarray (TMA). Seventy-seven MMs were immunostained on individual slides for maspin and p53 expression. Results were validated in 1 slide for each marker on a TMA system (TARP-2) with 498 tissue cores (0.6-mm diameter) from MM, other tumors, and normal tissue. The relationship between maspin and p53 in MM and carcinomas of other sites (breast, ovary, colon, lung, and prostate) was delineated using Pearson chi analysis. The inverse relationship between maspin and p53 expression predicted by hypothesized p53 regulation of maspin transcription, or any other correlation between these 2 markers, is not demonstrated in MM cases, using either classic individual slide (P=0.20) or TMA (P=0.85) methods when cutoffs for both markers are set at 10% or greater of cells staining. Even when cutoffs are altered with respect to either intensity or percentage of cells staining, no relationship is demonstrated between these markers, with either TMA or the conventional slide method. TMA immunostaining also showed no such relationship in carcinomas of the various other sites sampled-including breast and prostate, where previous studies have suggested a linkage. Despite published experimental evidence linking these 2 markers, this study failed to demonstrate correlation between maspin loss and p53 expression in MM using both individual slides and TMA, or in TMA of other carcinomas. Use of TMA is a quick, easy, and inexpensive method of immunohistochemical analysis of large numbers of cases, both to validate results obtained from individual slides and to assess specificity in a variety of neoplasms. However, heterogeneity and minimal tumor may lead to variable results.

Hierarchical cluster analysis of myoepithelial/basal cell markers in adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma

Distinguishing adenoid cystic carcinoma from polymorphous low-grade adenocarcinoma of the salivary glands is important for their management. We studied the expression of several myoepithelial and basal/stem cell markers (smooth muscle actin, calponin, smooth muscle myosin heavy chain, metallothionein, maspin, and p63) by immunohistochemistry in 23 adenoid cystic carcinoma and 24 polymorphous low-grade adenocarcinoma, to identify the most useful marker or combination of markers that may help their diagnoses. The results were analyzed using hierarchical cluster analysis and chi(2) test for trend. We noted diffuse expression of smooth muscle actin in 20 adenoid cystic carcinoma vs one polymorphous low-grade adenocarcinoma (P<0.0001), calponin in 15 adenoid cystic carcinoma vs one polymorphous low-grade adenocarcinoma (P<0.0001), smooth muscle myosin heavy chain in 15 adenoid cystic carcinoma vs one polymorphous low-grade adenocarcinoma (P=0.001), metallothionein in 22 adenoid cystic carcinoma vs eight polymorphous low-grade adenocarcinoma (P<0.001), maspin in 22 adenoid cystic carcinoma vs 14 polymorphous low-grade adenocarcinoma, and p63 in 21 adenoid cystic carcinoma vs 14 polymorphous low-grade adenocarcinoma. Hierarchical clustering of smooth muscle actin, calponin, smooth muscle myosin heavy chain, and metallothionein was virtually identical (kappa< or =0.0035), suggesting no significant advantage to their use in combination than individually. Diffuse smooth muscle actin expression showed the highest accuracy (91.5%) and positive predictive value (95.2%) for adenoid cystic carcinoma. Thus, diffuse expression of smooth muscle actin, calponin, smooth muscle myosin heavy chain, and metallothionein was highly predictive of adenoid cystic carcinoma, whereas maspin and p63 were frequently expressed in both tumors. In differentiating adenoid cystic carcinoma from polymorphous low-grade adenocarcinoma, smooth muscle actin as a single ancillary test in support of the histological findings, appears to be as efficient as multiple immunohistochemical tests.

Differential regulation of elafin in normal and tumor-derived mammary epithelial cells is mediated by CCAAT/enhancer binding protein beta

CCAAT/enhancer binding protein beta (C/EBP beta) is a transcription factor implicated in the control of development, differentiation, and proliferation of mammary epithelial cells. However, it remains unclear how C/EBP beta is involved in tumor suppression through its interaction with specific downstream genes in breast cancer. Tumor cells overexpress serine proteases, which play crucial roles in tumor invasion and metastasis. Elafin is an endogenous serine protease inhibitor and is transcriptionally down-regulated in most tumor cell lines. In this study, we show that C/EBP beta is differentially expressed in normal versus tumor cell lines and normal adjacent versus tumor tissues obtained from breast cancer patients. We identified elafin as a downstream effector of C/EBP beta and show that elafin is also differentially regulated between normal and tumor cells. The mechanism by which C/EBP beta regulates elafin expression is through its direct interaction with the elafin promoter. There are three C/EBP beta binding sites involved in the elafin promoter activity, and the overexpression of C/EBP beta transactivates the elafin gene through these sites in tumor cells. RNA interference studies in normal cells further evidenced the requirement of the C/EBP beta for the elafin expression and negative feedback loop between C/EBP beta and elafin. We suggest that elafin is a novel substrate of C/EBP beta, and alterations in C/EBP beta isoforms result in their differential binding to the elafin promoter, leading to the altered expression of the elafin between normal and tumor cells.

Epigenetic silencing of maspin expression occurs early in the conversion of keratocytes to fibroblasts

Maspin, a 42 kDa non-classical serpin (serine protease inhibitor) that controls cell migration and invasion, is mainly expressed by epithelial-derived cells but is also expressed in corneal stromal keratocytes. Upon culture of stromal keratocytes in the presence of FBS, maspin is down-regulated to nearly undetectable levels by passage two. DNA methylation is one of several processes that controls gene expression during cell differentiation, development, genetic imprinting, and carcinogenesis but has not been studied in corneal stromal cells. The purpose of this study was to determine whether DNA methylation of the maspin promoter and histone H3 dimethylation is involved in the mechanism of down-regulation of maspin synthesis in human corneal stromal fibroblasts and myofibroblasts. Human donor corneal stroma cells were immediately placed into serum-free defined medium or cultured in the presence of FBS and passed into serum-free medium or medium containing FBS or FGF-2 to induce the fibroblast phenotype or TGF-beta1 for the myofibroblast phenotype. These cell types are found in wounded corneas. The cells were used to prepare RNA for semi-quantitative or quantitative RT-PCR or to extract protein for Western analysis. In addition, P4 FBS cultured fibroblasts were treated with the DNA demethylating agent, 5-aza-2'-deoxycytidine (5-Aza-dC), and the histone deacetylase inhibitor, trichostatin A (TSA). Cells with and without treatment were harvested and assayed for DNA methylation using sodium bisulfite sequencing. The methylation state of histone H3 associated with the maspin gene in the P4 fibroblast cells was determined using a ChIP assay. Freshly harvested corneal stromal cells expressed maspin but upon phenotypic differentiation, maspin mRNA and protein were dramatically down-regulated. Sodium bisulfite sequencing revealed that the maspin promoter in the freshly isolated stromal keratocytes was hypomethylated while both the P0 stromal cells and the P1 cells cultured in the presence of serum-free defined medium, FGF-2 and TGF-beta1 were hypermethylated. Down-regulation of maspin synthesis was also associated with histone H3 dimethylation at lysine 9. Both maspin mRNA and protein were re-expressed at low levels with 5-Aza-dC but not TSA treatment. Addition of TSA to 5-Aza-dC treated cells did not increase maspin expression. Treatment with 5-Aza-dC did not significantly alter demethylation of the maspin promoter but did demethylate histone H3. These results show maspin promoter hypermethylation and histone methylation occur with down-regulation of maspin synthesis in corneal stromal cells and suggest regulation of genes upon conversion of keratocytes to wound healing fibroblasts can involve promoter and histone methylation.

RIN1 is a breast tumor suppressor gene

Breast cancer progression is driven by altered gene expression. We show that the RIN1 gene, which encodes a RAS effector regulating epithelial cell properties, is silenced in breast tumor cell lines compared with cultured human mammary epithelial cells. We also report that RIN1 is often reduced in human breast tumor cells compared with morphologically normal breast glandular cells. At least two silencing mechanisms seem to be involved. Overexpression of the transcription repressor SNAI1 (Snail) was observed in ZR75-1 cells, and SNAI1 knockdown restored RIN1 expression. In addition, DNA methylation within the RIN1 promoter and the first exon in KPL-1 cells suggested that epigenetic modifications may contribute to silencing, and demethylation was shown to restore RIN1 expression. Reexpression of RIN1 was shown to inhibit anchorage-independent growth in soft agar. In addition, RIN1 expression inhibited both the initiation and progression of tumorigenesis for two breast tumor cell lines in a mouse model, consistent with a tumor suppressor function. We also show that RIN1 acts as a negative regulator of tumor cell invasive growth and that this requires the ABL kinase-signaling function of RIN1, suggesting a mechanism through which RIN1 silencing may contribute to breast cancer progression.

Proteases as modulators of tumor-stromal interaction: primary tumors to bone metastases

As cells undergo oncogenic transformation and as malignant cells arrive at metastatic sites, a complex interplay occurs with the surrounding stroma. This dialogue between the tumor and stroma ultimately dictates the success of the tumor cells in the given microenvironment. As a result, understanding the molecular mechanisms at work is important for developing new therapeutic modalities. Proteases are major players in the interaction between tumor and stroma. This review will focus on the role of proteases in modulating tumor-stromal interactions of both primary breast and prostate tumors as well as at bone metastatic sites in a way that favors tumor growth.

Breast cancer metastases are molecularly distinct from their primary tumors

Metastases have been widely thought to arise from rare, selected, mutation-bearing cells in the primary tumor. Recently, however, it has been proposed that breast tumors are imprinted ab initio with metastatic ability. Thus, there is a debate over whether 'phenotypic' disease progression is really associated with 'molecular' progression. We profiled 26 matched primary breast tumors and lymph node metastases and identified 270 probesets that could discriminate between the two categories. We then used an independent cohort of breast tumors (81 samples) and unmatched distant metastases (32 samples) to validate and refine this list down to a 126-probeset list. A representative subset of these genes was subjected to analysis by in situ hybridization, on a third independent cohort (57 primary breast tumors and matched lymph node metastases). This not only confirmed the expression profile data, but also allowed us to establish the cellular origin of the signals. One-third of the analysed representative genes (4 of 11) were expressed by the epithelial component. The four epithelial genes alone were able to discriminate primary breast tumors from their metastases. Finally, engineered alterations in the expression of two of the epithelial genes (SERPINB5 and LTF) modified cell motility in vitro, in accordance with a possible causal role in metastasis. Our results show that breast cancer metastases are molecularly distinct from their primary tumors.

Angiogenesis inhibitors and the need for anti-angiogenic therapeutics

Angiogenesis is the formation of new blood vessels from pre-existing vessels to form capillary networks, which, among other diseases, such as diabetic retinopathy and macular degeneration, is particularly important for tumor growth and metastasis. Thus, depriving a tumor of its vascular supply by means of anti-angiogenic agents has been of great interest since its proposal in the 1970s. This review looks at the common angiogenic inhibitors (angiostatin, endostatin, maspin, pigment epithelium-derived factor, bevacizumab and other monoclonal antibodies, and zoledronic acid) and their current status in clinical trials.

Maspin is involved in bone matrix maturation by enhancing the accumulation of latent TGF-beta

Maspin, a serine protease inhibitor, is expressed by formative osteoblasts. The repression of maspin expression in osteoblastic cells decreased the level of latent TGF-beta in the extracellular matrix, whereas the overexpression of maspin increased latent TGF-beta. These findings suggest that maspin plays an important role in bone matrix formation, particularly in the accumulation of latent TGF-beta.

INTRODUCTION

Maspin is a serine protease inhibitor that exhibits tumor suppressive and anti-angiogenic activities. This study was performed to elucidate a possible role for maspin in bone formation.

MATERIALS AND METHODS

We performed immunohistochemical analysis of the expression of maspin during endochondral ossification. We evaluated the expression of maspin mRNA and protein in ROS 17/2.8 cells and primary rat osteoblastic cells by RT-PCR, immunocytochemistry, and Western blot analysis. We also examined the accumulation of TGF-beta in the extracellular matrix of cultured ROS 17/2.8 cells after transfection with vectors expressing either maspin or maspin antisense.

RESULTS

We observed expression of maspin by active osteoblasts in vivo. Rat osteoblastic cells also expressed maspin mRNA and protein in vitro. Moreover, the accumulation of latent TGF-beta in the extracellular matrix significantly decreased in cultures exposed to an anti-maspin antibody and when cells were transfected with a maspin antisense-expressing vector. In contrast, accumulation of latent TGF-beta in the extracellular matrix increased after transfection of cells with a vector expressing maspin.

CONCLUSIONS

These findings suggest that maspin expressed in active osteoblasts plays an important physiological role during maturation of the bone matrix, and in particular, during the process of accumulation of latent TGF-beta in the extracellular matrix.

Expression of VACM-1/cul5 mutant in endothelial cells induces MAPK phosphorylation and maspin degradation and converts cells to the angiogenic phenotype

Vasopressin-activated calcium mobilizing receptor (VACM-1) is a member of the cullin gene family involved in ubiquitin-proteosome dependent regulation of cellular functions. Expression of VACM-1 cDNA in cos-1 cells in vitro decreases basal cAMP levels and inhibits growth. The expression of (S730A)VACM-1 mutant cDNA, which removes PKA-dependent phosphorylation site in the VACM-1 cDNA sequence, reverses this phenotype. Since the expression of VACM-1 protein in vivo localizes largely to the vascular endothelial cells, in this study, we examined the effects of (S730A)VACM-1 cDNA expression on cellular signaling in the rat endothelial cell line RAMEC. Our results indicate that expression of (S730A)VACM-1 cDNA in RAMEC promotes cellular proliferation and induces angiogenic growth patterns. Western blot analyses indicate that (S730A)VACM-1 cDNA transfected cells express increased levels of Nedd8 modified VACM-1 and have higher levels of phosphorylated MAPK protein when compared to controls. Furthermore, expression of (S730A)VACM-1 cDNA induces translocation of the endogenous early response gene, egr-1, to the nucleus and leads to morphological changes that involve actin rearrangement. Finally, expression of (S730A)VACM-1 cDNA in RAMEC decreases concentration of maspin, a putative anti-angiogenic factor with a tumor suppressor activity. These results show that VACM-1 protein regulates endothelial cell growth and may modulate angiogenesis by a mechanism that involves MAPK phosphorylation, nuclear localization of egr-1, maspin expression, and actin polymerization.

Expression of the human Cathepsin L inhibitor hurpin in mice: skin alterations and increased carcinogenesis

The serine protease inhibitor (serpin) hurpin (serpin B13) is a cross class-specific inhibitor of the cysteine protease Cathepsin (Cat) L. Cat L is involved in lysosomal protein degradation, hair follicle morphogenesis, epidermal differentiation and epitope generation of antigens. Hurpin is a 44 kDa protein which is expressed predominantly in epidermal cells. In psoriatic skin samples, hurpin was strongly overexpressed when compared with normal skin. Keratinocytes overexpressing hurpin showed increased resistance towards UVB-induced apoptosis. To further analyse the functional importance of this inhibitor, we have generated transgenic mice with deregulated Cat L activity by expressing human hurpin in addition to the endogenous mouse inhibitor. The three independent transgenic lines generated were characterized by identical effects excluding insertional phenotypes. Macroscopically, mice expressing human hurpin are characterized by abnormal abdominal fur. The number of apoptotic cells and caspase-3 positive cells was reduced after UV-irradiation in transgenic animals compared with wild-type mice. Interestingly, after chemical carcinogenesis, transgenic mice showed an increased susceptibility to develop skin cancer. Array analysis of gene expression revealed distinct differences between wild-type and hurpin-transgenic mice. Among others, differentially expressed genes are related to antigen presentation and angiogenesis. These results suggest an important role of Cat L regulation by hurpin which might be of clinical relevance in human skin diseases.

ATF-2 controls transcription of Maspin and GADD45α genes independently from p53 to suppress mammary tumors

The activating transcription factor, ATF-2, is a target of p38 and JNK that are involved in stress-induced apoptosis. Heterozygous Atf-2 mutant (Atf-2+/-) mice are highly prone to mammary tumors. The apoptosis-regulated gene GADD45alpha and the breast cancer suppressor gene Maspin, both of which are known to be p53 target genes, are downregulated in the mammary tumors arisen in Atf-2+/- mice. Here, we have analysed how ATF-2 controls the transcription of GADD45alpha and Maspin. ATF-2 and p53 independently activate the GADD45alpha transcription. ATF-2 does not directly bind to the GADD45alpha promoter; instead, it is recruited via Oct-1 and NF-I. ATF-2 simultaneously binds to Oct-1, NF-I and breast cancer suppressor BRCA1 to activate transcription. With regard to Maspin, ATF-2 and p53 directly bind to different sites in the Maspin promoter to independently activate its transcription. Consistent with the observation that ATF-2 and p53 independently activate the transcription of Maspin and GADD45alpha is that the loss of one copy of p53 shortened the period required for mammary tumor development in Atf-2+/- mice. These studies suggest the functional link between the ATF-2 and the two tumor suppressors BRCA1 and p53.

Chromosomal imbalances in oral squamous cell carcinoma: examination of 31 cell lines and review of the literature

Classical and molecular cytogenetic analysis, including fluorescence in situ hybridization (FISH) and chromosomal comparative genomic hybridization (CGH), were used to examine genetic changes involved in the development and/or progression of oral squamous cell carcinoma (OSCC). Of 31 OSCC cell lines studied, more than one-third expressed clonal structural abnormalities involving chromosomes 3, 7, 8, 9, and 11. Eleven OSCC cell lines were evaluated using CGH to identify novel genome-wide gains, losses, or amplifications. By CGH, more than half of the cell lines showed loss of 3p, gain of 3q, 8q, and 20q. Further, molecular cytogenetic analyses by FISH of primary tumors showed that the karyotypes of cell lines derived from those tumors correlated with specific gains and losses in the tumors from which they were derived. The most frequent nonrandom aberration identified by both karyotype and CGH analyses was amplification of chromosomal band 11q13 in the form of a homogeneously staining region. Our data suggest that loss of 9p and 11q13 amplification may be of prognostic benefit in the management of OSCC, which is consistent with the literature. The results of this study validate the relationship between these OSCC cell lines and the tumors from which they were derived. The results also emphasize the usefulness of these cell lines as in vitro experimental models and provide important genetic information on these OSCC cell lines that were recently reported in this journal.

SERPINB11 Is a New Noninhibitory Intracellular Serpin

SERPINB11, the last of 13 human clade B serpins to be described, gave rise to seven different isoforms. One cDNA contained a premature termination codon, two contained splice variants, and four contained full-length open reading frames punctuated by eight single nucleotide polymorphisms (SNPs). The SNPs encoded amino acid variants located within the serpin scaffold but not the reactive site loop (RSL). Although the mouse orthologue, Serpinb11, could inhibit trypsin-like peptidases, SERPINB11 showed no inhibitory activity. To determine whether the human RSL targeted a different class of peptidases or the serpin scaffold was unable to support inhibitory activity, we synthesized chimeric human and mouse proteins, in which the RSLs had been swapped. The human RSL served as a trypsin inhibitor when supported by mouse scaffold sequences. Conversely, the mouse RSL on the human scaffold showed no inhibitory activity. These findings suggested that variant residues in the SERPINB11 scaffold impaired serpin function. SDS-PAGE analysis supported this notion as RSL-cleaved SERPINB11 was unable to undergo the stressed-to-relaxed transition typical of inhibitory type serpins. Mutagenesis studies supported this hypothesis, since the reversion of amino acid sequences in helices D and I to those conserved in other clade B serpins partially restored the ability of SERPINB11 to form covalent complexes with trypsin. Taken together, these findings suggested that SERPINB11 SNPs encoded amino acids in the scaffold that impaired RSL mobility, and HapMap data showed that the majority of genomes in different human populations harbored these noninhibitory SERPINB11 alleles. Like several other serpin superfamily members, SERPINB11 has lost inhibitory activity and may have evolved a noninhibitory function.

Focal degeneration of basal cells and the resultant auto-immunoreactions: a novel mechanism for prostate tumor progression and invasion

The development of human prostate cancer is believed to be a multistep process, progressing sequentially from normal, to hyperplasia, to prostatic intraepithelial neoplasia (PIN), and to invasive and metastatic lesions. High grade PIN has been generally considered as the direct precursor of invasive lesions, and the progression of PIN is believed to be triggered primarily, if not solely, by the overproduction of proteolytic enzymes predominately by cancer cells, which result in the degradation of the basement membrane. These theories, however, are hard to reconcile with two main facts: (1) only about 30% untreated PIN progress to invasive stage, while none of the current approaches could accurately identify the specific PIN or individuals at greater risk for progression, and (2) results from recent world-wide clinical trials with a wide variety of proteolytic enzyme inhibitors have been very disappointing, casting doubt on the validity of the proteolytic enzyme theory. Since over 90% of prostate cancer-related deaths result from invasion-related illness and the incidence of PIN could be up to 16.5-25% in routine or ultrasound guided prostate biopsy, there is an urgent need to uncover the intrinsic mechanism of prostate tumor invasion. Promoted by the facts that the basal cell population is the source of several tumor suppressors and the absence of the basal cell layer is the most distinct feature of invasive lesions, our recent studies have intended to identify the early alterations of basal cell layers and their impact on tumor invasion using multidisciplinary approaches. Our studies revealed that a subset of pre-invasive tumors contained focal disruptions (the absence of basal cells resulting in a gap greater than the combined size of at least three epithelial cells) in surrounding basal cell layers. Compared to their non-disrupted counterparts, focally disrupted basal cell layers had several unique features: (1) significantly lower proliferation; (2) significantly lower p63 expression; (3) significantly higher apoptosis; and (4) significantly higher leukocyte infiltration and stromal reactions. Compared to their counterparts distant from focal disruptions or overlying non-disrupted basal cell layers, epithelial cells overlying focal basal cell layer disruptions showed the following unique features: (1) significantly higher proliferation; (2) significantly higher expression of cell cycle control-, cell growth-, and stem cell-related genes; and (3) physical continuity with adjacent invasive lesions. Together, these findings suggest that focal basal cell layer disruptions could substantially impact the molecular profile and biological presentations of the overlying epithelial cells. Based on these and other findings, we have proposed that prostate tumor invasion is triggered by a localized degeneration of aged or injured basal cells and the resultant auto-immunoreactions. Our hypothesized steps for prostate tumor invasion include the following: (1) due to inherited or environmental factors, some patients contained cell cycle control- and renewal-related defects in the basal cell population that cause elevated basal cell degenerations; (2) the degradation products of degenerated basal cells or diffusible molecules of the overlying epithelial cells attract leukocyte infiltration; (3) leukocytes discharge their digestive enzymes upon the direct physical contact, resulting in a focal disruption in the basal cell layer, which leads to several focal alterations: (a) a focal loss of tumor suppressors and paracrine inhibitory function; (b) a focal increase of the permeability for growth-required nutrients and oxygen; (c) a focal increase of growth factors; (d) direct physical contact between epithelial and stromal cells; and (e) the exposure of the overlying epithelial cells directly to the stromal tissue fluid. These alterations individually or collectively stimulate or favor a clonal proliferation and stromal invasion of tumor progenitor or stem cells. Our hypothesis differs from the traditional theories in several aspects, including the triggering factor for the initiation of tumor invasion, the stage of tumor invasion, the cellular origin of invasive lesions, the significance of immunoreactive and stromal cells, and the potential approaches for early detection, treatment, and prevention of invasion. Our hypothesis represents a novel in vivo model as to the cellular mechanism leading to prostate tumor invasion. If confirmed, it could lead to a new direction to search for more effective approaches to combat prostate cancer. It could also have an immediate impact on patient care through improved pathologic evaluation of prostate tumor biopsies. More importantly, our hypothesis might be applicable, and significantly impact the detection, treatment, and prevention of other epithelium-derived tumors.

Double immunohistochemical staining with MUC4/p53 is useful in the distinction of pancreatic adenocarcinoma from chronic pancreatitis: a tissue microarray-based study

CONTEXT

Immunohistochemical stains have been used for the distinction of pancreatic adenocarcinoma from chronic pancreatitis.

OBJECTIVE

To determine if a double stain for MUC/p53 improved specificity and sensitivity for distinction of pancreatic adenocarcinoma from chronic pancreatitis by comparing maspin, mucin 4 (MUC4), p53, Smad4, and the double stain MUC4/p53.

DESIGN

Seventy-four pancreatic adenocarcinomas and 19 chronic pancreatitis cases were retrieved from archival files. Tissue cores were arrayed to create a tissue microarray of 2-mm cores. Sections were stained with antibodies against maspin, MUC4, p53, and Smad4. Additionally, a 2-color, double stain for MUC4 and p53 was developed and evaluated. Five percent or greater staining in either of the cores was considered positive. Intensity (0, 1, 2) and extent (%) of tumor cells staining was also determined.

RESULTS

The sensitivity for distinction of pancreatic adenocarcinoma from chronic pancreatitis with maspin, MUC4, p53, and Smad4 was 90%, 77%, 60%, and 63%, respectively; the specificity was 67%, 78%, 88%, and 88%, respectively. When MUC4 and p53 were combined in a double stain, and positive staining for either considered a positive result, the sensitivity increased to 96% but specificity was 73%. When immunoreactivity for both antibodies was necessary for a positive result, sensitivity fell to 39% but specificity was 100%. No correlation was found between intensity or extent of staining with any of the individual stains and tumor differentiation.

CONCLUSION

The double immunohistochemical stain for MUC4/p53 can be a useful diagnostic tool in conjunction with the hematoxylin-eosin-stained section for pancreatic adenocarcinoma, particularly when limited tumor is available for multiple stains.

SIRPalpha1 and SIRPalpha2: their role as tumor suppressors in breast carcinoma cells

We have previously reported that expression of SIRPalpha1/SHPS-1 was strongly suppressed in v-Src-transformed cells and its forced expression resulted in the suppression of anchorage-independent growth of the cells [K. Machida, S. Matsuda, K. Yamaki, T. Senga, A.A. Thant, H. Kurata, K. Miyazaki, K. Hayashi, T. Okuda, T. Kitamura, T. Hayakawa, M. Hamaguchi, v-Src suppresses SHPS-1 expression via the Ras-MAP kinase pathway to promote the oncogenic growth of cells, Oncogene 19 (2000) 1710-1718]. We examined the effect of human SIRPalpha1 expression in breast cancer cell lines, Hs578T and MCF7, and compared with the effect of SIRPalpha2 expression in Hs578T. Forced expression of either SIRPalpha1 or SIRPalpha2 did not perturb the growth of Hs578T in a conventional attached condition. Their expression, however, enforced the actin stress fiber formation and induced activation of Rho, but not Rac, in Hs578T cells. Moreover, forced expression of either SIRPalpha1 or SIRPalpha2 displayed distinct suppressive effect on the anchorage-independent growth of Hs578T cells. Similarly, forced expression of SIRPalpha1 in MCF7 specifically suppressed the anchorage-independent growth of the cells. Taken together, our results strongly suggest the function of SIRPalpha1 and 2 as type II tumor suppressors for human breast carcinoma.

Maspin Binds to Urokinase-type and Tissue-type Plasminogen Activator through Exosite-Exosite Interactions

Maspin is a member of the serpin family with a reactive center loop that is incompatible with proteinase inhibition by the serpin conformational change mechanism. Despite this there are reports that maspin might regulate uPA-dependent processes in vivo. Using exogenous and endogenous fluorescence, we demonstrate here that maspin can bind uPA and tPA in both single-chain and double-chain forms, with K(d) values between 300 and 600 nM. Binding is at an exosite on maspin close to, but outside of, the reactive center loop and is therefore insensitive to mutation of Arg(340) within the reactive center loop. The binding site on tPA does not involve the proteinase active site, with the result that maspin can bind to S195A tPA that is already complexed to plasminogen activator inhibitor-1. The ability of maspin to bind these proteinases without involvement of the reactive center loop leaves the latter free to engage in additional, as yet unidentified, maspin-protein interactions that may serve to regulate the properties of the exosite-bound proteinase. This may help to reconcile apparently conflicting studies that demonstrate the importance of the reactive center loop in certain maspin functions, despite the inability of maspin to directly inhibit tPA or uPA catalytic activity in in vitro assays through engagement between its reactive center loop and the active site of the proteinase.

Immunohistochemical detection of uPA, uPAR, PAI-1, and maspin in ameloblastic tumors

BACKGROUND

To evaluate the roles of extracellular matrix (ECM)-degrading serine proteinase in progression of odontogenic tumors, expression of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), plasminogen activator inhibitor-1 (PAI-1), and maspin was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 10 tooth germs, 45 ameloblastomas, and 5 malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against uPA, uPAR, PAI-1, and maspin.

RESULTS

Immunohistochemical reactivity for uPA, uPAR, PAI-1, and maspin was detected in normal and neoplastic odontogenic tissues: uPA was recognized predominantly in mesenchymal cells, uPAR was evident in epithelial cells, PAI-1 was found in both epithelial and mesenchymal cells, and maspin was expressed only in epithelial cells. The levels of uPA and uPAR immunoreactivity in ameloblastic tumors were slightly higher than the levels in tooth germs, while PAI-1 reactivity in ameloblastomas tended to be lower than that in tooth germs. The level of maspin immunoreactivity in ameloblastomas was significantly higher than that in tooth germs, and ameloblastic carcinoma showed decreased maspin reactivity.

CONCLUSION

Expression of uPA, uPAR, PAI-1, and maspin in tooth germs and ameloblastic tumors suggests that interactions among these molecules contribute to ECM degradation and cell migration during tooth development and tumor progression. Altered expression of the serine proteinase and its associated molecules in ameloblastic tumors may be involved in oncogenesis of odontogenic epithelium.

Novel functional interaction between Na+/H+exchanger 1 and tyrosine phosphatase SHP-2

Besides being a intracellular pH (pHi) regulator, Na+/H+exchanger (NHE)1 has recently been postulated as a membrane scaffold that assembles protein complexes and coordinates various signaling pathways. The aim of the present study was to uncover NHE1 interactive partners and study their functional implications. NHE1 interactive partners were screened in the mouse brain with a signal transduction AntibodyArray. Ten of 400 tested proteins appeared to be potentially associated with NHE1. These partners have been shown to be involved in either cell proliferative or apoptotic pathways. The interactions between NHE1 and Src homology 2 domain-containing protein tyrosine phosphatase (SHP-2), Bin1, and heat shock protein (HSP)70 were reciprocally confirmed by coimmunoprecipitation. Moreover, in vitro binding data have shown that NHE1 COOH terminus interacts directly with SHP-2. The functional significance of the association between NHE1 and SHP-2 was further investigated by measuring pHi, cell proliferation, and cell death with the fluorescent dye BCECF, [3H]thymidine incorporation, and medium lactate dehydrogenase activity, respectively. Our results revealed that cells with SHP-2 overexpression exhibited a higher steady-state pHiand a faster, NHE1-dependent pHirecovery rate from acid load in HEPES buffer. In addition, SHP-2 overexpression diminished the HOE-642-induced inhibition of cell proliferation and protected cells from hypoxic injury, especially in the presence of HOE-642. Together, our findings demonstrate that SHP-2 not only is physically associated with NHE1 but also modulates NHE1 functions such as pHiregulation, cell proliferation, and cell death under hypoxia.

Focal degeneration of aged or injured myoepithelial cells and the resultant auto-immunoreactions are trigger factors for breast tumor invasion

The development of breast cancer is believed to be a multi-step process, sequentially progressing from normal to hyperplastic, to in situ, and to invasive stages. The progression from the in situ to invasive stage is believed to be triggered primarily, if not solely, by the overproduction of proteolytic enzymes by cancer cells, which cause degradation of the basement membrane. This theory is consistent with data derived from studies with cell cultures or animal models, while results from recent worldwide clinical trials with a variety of proteolytic enzyme inhibitors have been very disappointing, casting doubt on the validity of the enzyme theory. Based on our recent studies, we propose that breast tumor invasion is triggered by the following mechanisms and events: (1) the predisposition of genetic abnormalities in ME cell replenishment-related genes or other insults results in elevated focal degeneration of ME cells in some individuals; (2) the degradation products of ME cells or diffusible molecules of epithelial cells attract infiltration of immunoreactive cells (IRC) into the affected sites; (3) the direct physical contact between IRC and degenerated ME cells results in the discharge of digestive enzymes from IRC, causing focal disruptions in the ME cell layer; (4) focal disruptions in a given ME cell layer result in a localized loss of tumor suppressors and paracrine inhibitory function, a focal increase of permeability for oxygen, nutrients, and growth factors, and a localized increase of leukocyte infiltration, which facilitate the monoclonal proliferation of tumor progenitors, forming a biologically more aggressive cell cluster overlying the disrupted ME cell layer; (5) the direct physical contact between the newly formed cell cluster and stromal cells stimulates the production of tenascin and other invasion-associated molecules that facilitate tissue remodeling, angiogenesis, and epithelial-mesenchymal transition, providing a favorable micro-environment for proliferation and invasion. Our hypothesis differs from the enzyme theory in the stage of tumor invasion, the cellular origin of invasive lesions, the significance of IRC and stromal cells, and the potential approaches for treatment and prevention. If confirmed, our hypothesis could facilitate the early detection of specific individuals at increased risk to develop invasive breast cancer. More importantly, our hypothesis may facilitate development of novel approaches, including stimulating ME cell growth, neutralizing ME cell degradation products, manipulating the types and extent of IRC infiltration, and controlling the extent of stromal reactions, to combat tumor invasion.

Paradoxical expression of maspin in gastric carcinomas: correlation with carcinogenesis and progression

Maspin, a serine protease inhibitor related to the serpin family, can suppress invasion and metastasis of malignancies. To clarify the role of maspin in the genesis and progression of gastric carcinomas, its expression pattern and level were studied by immunohistochemistry on tissue microarrays containing gastric carcinoma (n = 237), normal gastric mucosa (n = 23), intestinal metaplasia (n = 38), and adenoma (n = 42); and the findings were compared with clinicopathological parameters. Furthermore, maspin expression in the gastric carcinoma cell lines (HCG-27, MKN28, and MKN45) was examined by immunohistochemistry and Western blotting. We found that cytoplasmic and nuclear maspin expression paralleled each other (P < .05) and decreased from intestinal metaplasia, adenoma, and carcinoma to normal gastric mucosa (P < .05). A significant positive association was noted with depth of invasion, lymphatic invasion, lymph node metastasis, and TNM stage (P < .05) but not with sex or Lauren's classification (P > .05). Univariate and multivariate analyses indicated that expression of maspin correlated negatively with cumulative patient survival in gastric carcinoma (P < .05) but was not an independent factor in the prognosis. The 2 independent factors, depth of invasion and lymphatic invasion, influenced the relation between nuclear maspin expression and survival, whereas only depth of invasion correlated with cytoplasmic maspin. Our study indicated that maspin expression experiences upregulation in gastric precancerous lesions and then slight downregulation with malignant transformation. High expression may paradoxically promote invasion and metastasis of gastric carcinomas and could be considered a good marker for the pathobiological behaviors of gastric carcinomas.

Altered protein expression at early-stage rat hepatic neoplasia

Protein expression patterns were analyzed in a rat model of hepatic neoplasia to detect changes reflecting biological mechanism or potential therapeutic targets. The rat resistant hepatocyte model of carcinogenesis was studied, with a focus on the earliest preneoplastic lesion visible in the liver, the preneoplastic hyperplastic nodule. Expression differences were shown by two-dimensional polyacrylamide gel electrophoresis and image analysis. Polypeptide masses were measured by peptide mass fingerprinting using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) and their sequences were obtained by tandem mass spectrometry. Alterations in expression of cytoskeletal and functional proteins were demonstrated, consistent with biological changes known to occur in the preneoplastic cells. Of particular interest was the differential expression of a serine protease inhibitor (serpin) with a role implicated in angiogenesis. Serpin, implicated in the inhibition of angiogenesis, is present in normal liver but has greatly reduced expression at the preneoplastic stage of liver cancer development. Immunofluorescence microscopy with antibodies to this serpin, kallistatin, supports the proteomic identification. Immunofluorescence microscopy with antibodies to the blood vessel marker von Willebrand factor provides evidence for neovascularization in the liver containing multiple preneoplastic nodules. These observations suggest that at an early stage of liver carcinogenesis reduction or loss of angiogenesis inhibitors may contribute to initiation of neoangiogenesis. A number of other identified proteins known to be associated with hepatomas are also present at early-stage neoplasia.

Prognostic significance of maspin in pancreatic ductal adenocarcinoma: tissue microarray analysis of 223 surgically resected cases

Maspin (SERPINB5), a serine proteinase inhibitor, was first identified as a potential tumor suppressor on the basis of its differential expression between normal mammary epithelial cells and human breast carcinoma cell lines. Recent studies have shown that maspin might be a prognostic tumor marker. Pancreatic ductal adenocarcinoma acquires maspin expression through hypomethylation of the maspin promoter. However, no study has investigated the prognostic significance of maspin expression in pancreatic ductal adenocarcinomas. In this study, we investigated maspin protein expression in a large series of 223 surgically resected pancreatic ductal adenocarcinomas using immunohistochemical staining and high throughput tissue microarrays. Maspin expression was correlated with postoperative survival and other clinicopathologic factors. Maspin was detected in 209 of these 223 (94% cases) pancreatic ductal adenocarcinomas including 39 (18% cases) focal (5-50% tumor cells) and 170 (76% cases) diffuse (>50% tumor cells). Fourteen (or 6% cases) pancreatic ductal adenocarcinomas did not show maspin expression by immunohistochemical staining (<5% tumor cells). Normal ductal epithelium is not labeled with maspin. Overexpression of maspin in pancreatic ductal adenocarcinoma is associated with worse postoperative survival especially in patients whose tumors exhibit diffuse expression of maspin. After adjusting other clinicopathologic factors, maspin expression remains to be an independent adverse prognosticator for postoperative survival. Maspin expression is not associated with patient age, gender, tumor size, tumor pathologic stage, lymph node status, and vascular invasion or perineural invasion. Nuclear labeling of maspin is associated with better tumor differentiation although this staining pattern is not associated with a better prognosis. In addition, maspin overexpression is also observed in 48% low-grade (grades 1a and 1b) pancreatic intraepithelial neoplasias (PanINs) and 78% high-grade (grades 2 and 3) PanINs, suggesting that maspin upregulation occurs early during the multi-step progression model of pancreatic ductal adenocarcinoma.

Maspin augments proteasome inhibitor-induced apoptosis in prostate cancer cells

Proteasome inhibitors are known to induce apoptosis in a variety of cancer cells. On the other hand, maspin, a non-inhibitory serine protease inhibitor, is shown to sensitize cancer cells to therapeutic agents that induce apoptosis. We examined the consequence of maspin expression in prostate cancer cells targeted for treatment with various proteasome inhibitors. We observed that proteasome inhibitors induced apoptosis more effectively in maspin transfected human prostate cancer DU145 cells than in control cells. Interestingly, increased apoptosis in these cells was associated with a significant induction of maspin expression. MG-132, a proteasome inhibitor, induced endogenous and ectopic [cytomegalovirus promoter (CMV)-driven] maspin expression, and maspin siRNA attenuated MG-132-induced apoptosis. Proteasome inhibitor-induced maspin expression was inhibited by actinomycin D (Act D) and cyclohexamide (CHX), and by the inhibitors of p38MAPK, but not ERK1/2 or NF-kappaB. Electrophoretic mobility-shift assay (EMSA) and promoter-reporter activity analyses suggested that p38MAPK activated transcription factor AP-1 is responsible for proteasome inhibitor-induced maspin expression. Taken together, these observations demonstrate that proteasome inhibitors induce maspin expression by activating p38MAPK pathway, and that maspin thus expressed, in turn, augments proteasome inhibitor-induced apoptosis in prostate cancer cells. Our results suggest that gene therapy involving ectopic maspin expression may dramatically improve the efficacy of proteasome inhibitors for the treatment of prostate cancer.

Gum mastic increases maspin expression in prostate cancer cells

AIM

To study whether gum mastic, a natural resin, can regulate maspin expression in prostate cancer cells, and further investigate the mechanisms involved in this regulatory system.

METHODS

RT-PCR and Western blotting were used to detect maspin expression at the transcriptional and translational levels. Reporter gene assay was used to investigate the effect of gum mastic on the maspin promoter. The binding activity of negative androgen-responsive element (ARE) and positive Sp1 element in the maspin promoter were studied by electrophoretic mobility shift assay.

RESULTS

Gum mastic induced maspin mRNA and protein expression, and the maspin promoter activity was enhanced with gum mastic treatment. Finally, gum mastic inhibited the ARE binding activity and increased the Sp1 binding activity in the maspin promoter.

CONCLUSION

Gum mastic enhances maspin promoter activity by suppressing ARE binding activity and enhancing Sp1 binding activity, and the increased activity in the maspin promoter finally leads to the up-regulation of both its mRNA and protein levels.

Nuclear cytokine-activated IKKalpha controls prostate cancer metastasis by repressing Maspin

Inflammation enhances tumour promotion through NF-kappaB-dependent mechanisms. NF-kappaB was also proposed to promote metastatogenesis through epithelial-mesenchymal transition. Yet a mechanistic link between inflammation and metastasis is missing. We identified a role for IkappaB kinase alpha (IKKalpha), activated by receptor activator of NF-kappaB (RANK/TNFRSF11A), in mammary epithelial proliferation during pregnancy. Owing to similarities between mammary and prostate epithelia, we examined IKKalpha involvement in prostate cancer and its progression. Here we show that a mutation that prevents IKKalpha activation slows down CaP growth and inhibits metastatogenesis in TRAMP mice, which express SV40 T antigen in the prostate epithelium. Decreased metastasis correlated with elevated expression of the metastasis suppressor Maspin, the ablation of which restored metastatic activity. IKKalpha activation by RANK ligand (RANKL/TNFSF11) inhibits Maspin expression in prostate epithelial cells, whereas repression of Maspin transcription requires nuclear translocation of active IKKalpha. The amount of active nuclear IKKalpha in mouse and human prostate cancer correlates with metastatic progression, reduced Maspin expression and infiltration of prostate tumours with RANKL-expressing inflammatory cells. We propose that tumour-infiltrating RANKL-expressing cells lead to nuclear IKKalpha activation and inhibition of Maspin transcription, thereby promoting the metastatic phenotype.

Stage specific gene expression of serpins and their cognate proteases during myeloid differentiation

Proteases and their serpin inhibitors are abundantly expressed in haemopoietic and peripheral blood cells. There is, however, relatively little information about the role played by serpins in the control of protease activity within these cells and in the pericellular region. The observation that mutations in the neutrophil elastase gene, which cause cyclic and severe congenital neutropenia, are associated with protease maldistribution gives some clue as to the potential importance of inhibitor proteins. To begin to address the role of protease/inhibitor balance in blood cells we used reverse transcription polymerase chain reaction to examine protease and serpin gene expression in mature peripheral blood cells, differentiating haemopoietic progenitors, leukaemic blasts and haemopoietic cell lines. The results demonstrate stage-specific expression of proteases together with widespread expression of intra- and extra-cellular serpins. The elastase inhibitors monocyte neutrophil elastase inhibitor (MNEI) and antitrypsin (AT) showed overlapping expression. MNEI is predominantly expressed in early haemopoietic progenitors while antitrypsin is mainly expressed in more mature myeloid precursors, peripheral blood granulocytes and mononuclear cells. Our results give an overall picture of serpin and protease gene expression and draws attention to the potential importance of elastase regulators at all stages of myelopoiesis.

Maspin is Useful in the Distinction of Pancreatic Adenocarcinoma From Chronic Pancreatitis

Maspin, a member of the serpin family of serine protease inhibitors, has been shown to limit invasion and metastases in breast and prostate carcinomas. Maspin gene expression is up-regulated in pancreatic cancer, but not in normal pancreatic tissue. Maspin expression has been documented using immunohistochemical studies in pancreatic adenocarcinoma and high-grade intraductal dysplasia. We studied pancreatic ductal adenocarcinomas and chronic pancreatitis utilizing tissue microarray technology to determine the utility of maspin in differentiating these lesions. Immunohistochemistry was performed on tissue microarrays made from 72 cases of pancreatic ductal adenocarcinoma and 24 cases of chronic pancreatitis. Carcinomas were graded as well, moderately, or poorly differentiated using the WHO criteria. The primary antibody used was monoclonal antimaspin antibody (clone G167-70, 1:800, PharMingen, San Diego, CA). Nuclear and/or cytoplasmic staining for maspin was qualitatively scored from 1 + to 3 + based on intensity. Cases were considered positive if one or more cores demonstrated staining. Cases of chronic pancreatitis showed focal, weak (1 + to 2 +) staining within occasional benign ductal epithelial cells in 29% of cases (7/24). Diffuse and intense (3 +) staining was present in ducts with squamous metaplasia (3 cases). The majority of ducts showed no staining. Ductal adenocarcinomas showed diffuse staining in 91% (66/72) of cases with generally more intense staining than cases of chronic pancreatitis. Maspin may be helpful in differentiating ductal adenocarcinoma from chronic pancreatitis, once squamous metaplasia is ruled out.

Convergence of p53 and transforming growth factor beta (TGFbeta) signaling on activating expression of the tumor suppressor gene maspin in mammary epithelial cells

Using two-dimensional difference gel electrophoresis, we identified the tumor suppressor gene maspin as a transforming growth factor beta (TGFbeta) target gene in human mammary epithelial cells. TGFbeta up-regulatesMaspin expression both at the RNA and protein levels. This up-regulation required Smad2/3 function and intact p53-binding elements in the Maspin promoter. DNA affinity immunoblot and chromatin immunoprecipitation revealed the presence of both Smads and p53 at the Maspin promoter in TGFbeta-treated cells, suggesting that both transcription factors cooperate to induce Maspin transcription. TGFbeta did not activate Maspin-luciferase reporter in p53-mutant MDA-MB-231 breast cancer cells, which exhibit methylation of the endogenous Maspin promoter. Expression of ectopic p53, however, restored ligand-induced association of Smad2/3 with a transfected Maspin promoter. Stable transfection of Maspin inhibited basal and TGFbeta-stimulated MDA-MB-231 cell motility. Finally, knockdown of endogenous Maspin in p53 wild-type MCF10A/HER2 cells enhanced basal and TGFbeta-stimulated motility. Taken together, these data support cooperation between the p53 and TGFbeta tumor suppressor pathways in the induction of Maspin expression, thus leading to inhibition of cell migration.

A role of novel serpin maspin in tumor progression: the divergence revealed through efforts to converge

Maspin, a 42 kDa protein, belongs to the serine protease inhibitor (serpin) superfamily and is more closely related to the ovalbumin-like serpin subfamily (ov-serpins). More than a decade after the discovery of the maspin gene, our pursuit of the molecular mechanisms of maspin revealed a significant divergence of maspin from other serpins. This review article summarizes recent advances in the identification of maspin-binding proteins and the potential underlying molecular mechanisms of maspin in tumor progression. Specifically, the molecular interactions of maspin with the cell surface-associated pro-urokinase-type plasminogen activator (pro-uPA) and intracellular histone deacetylase 1 (HDAC1) are highlighted. Our new evidence suggests a new paradigm that maspin acts as a serpin-like molecule to inhibit serine protease-like targets. From an evolution point of view, the uniquely important function of maspin in development and tumor progression is likely due to its ancestral sequence code, and accordingly, its novel "meta"-serpin structure. It is reasonable to hypothesize that the conservation of a serine protease-like catalytic center in many molecules requires the co-existence of endogenous antagonists. The unique inhibitory interaction of maspin with both HDAC1 and pro-uPA might not be substituted by other serpins that have evolved to acquire higher target specificities. Thus, tumor suppressive maspin offers a unique therapeutic opportunity.

The clinical significance of disseminated tumor cells in breast cancer

The presence of tumor cells in the bone marrow of primary breast cancer patients at surgery has been shown to be an independent prognostic indicator of relapse. Tumor cells have been detected either directly, using immunocytochemical staining, or indirectly, using reverse transcription-polymerase chain reaction (RT-PCR). Studies have been initiated to determine whether the presence of disseminated cells can be monitored during the therapy of patients with primary breast cancer, and thus potentially be used to predict relapse before overt metastases are detectable. Studies are also ongoing to improve methods of detection, such as immunobead enrichment followed by staining and real-time RT-PCR, and to find alternative markers for the disseminated cells. Studies of patients with overt metastases have shown that there is a large tumor load in the peripheral blood and that this predicts overall survival. This article reviews the published literature on studies carried out in both primary and metastatic breast cancer patients, the methodologies and markers used, and improvements in detection methodologies that are being investigated including real-time RT-PCR, novel markers, enrichment and automated image analysis.

Maspin controls mammary tumor cell migration through inhibiting Rac1 and Cdc42, but not the RhoA GTPase

Rac1 and Cdc42 are members of the Rho family of small GTPases that play essential roles in diverse cellular functions, including cell migration. The activities of these Rho family proteins are controlled by growth factor receptor activation and cell-ECM interactions. Here, we show that maspin, a well-documented tumor suppressor gene, also controls cell motility through inhibiting Rac1/Cdc42 activity. Using the GST-PAK and GST-Rho binding protein pull-down assays for GTP-bound Rac1, Cdc42, and RhoA, we showed that treatment of MDA-MB-231 tumor cells with recombinant maspin for a short time period significantly inhibited the activity of Rac1 and Cdc42, but not RhoA. The reactive site loop (RSL) within maspin protein is the functional domain involved in the inhibition. Maspin mutants with the RSL deleted or a point mutation in the RSL region lost their inhibitory activity. We further examined the ability of maspin to inhibit Rac1- and Cdc42-mediated signaling pathways and transcription factors. Treatment of MDA-MB-231 cells with maspin led to the inhibition of JNK kinase activity as assayed by immuno-kinase assays. In addition, the AP-1 transcription activity downstream of JNK kinase pathway was also reduced. Together, we have identified Rac1 and Cdc42 as the downstream targets that mediate the inhibition of mammary tumor cell migration by maspin.

Reduced levels of ATF-2 predispose mice to mammary tumors

Transcription factor ATF-2 is a nuclear target of stress-activated protein kinases, such as p38, which are activated by various extracellular stresses, including UV light. Here, we show that ATF-2 plays a critical role in hypoxia- and high-cell-density-induced apoptosis and the development of mammary tumors. Compared to wild-type cells, Atf-2(-/-) mouse embryonic fibroblasts (MEFs) were more resistant to hypoxia- and anisomycin-induced apoptosis but remained equally susceptible to other stresses, including UV. Atf-2(-/-) and Atf-2(+/-) MEFs could not express a group of genes, such as Gadd45alpha, whose overexpression can induce apoptosis, in response to hypoxia. Atf-2(-/-) MEFs also had a higher saturation density than wild-type cells and expressed lower levels of Maspin, the breast cancer tumor suppressor, which is also known to enhance cellular sensitivity to apoptotic stimuli. Atf-2(-/-) MEFs underwent a lower degree of apoptosis at high cell density than wild-type cells. Atf-2(+/-) mice were highly prone to mammary tumors that expressed reduced levels of Gadd45alpha and Maspin. The ATF-2 mRNA levels in human breast cancers were lower than those in normal breast tissue. Thus, ATF-2 acts as a tumor susceptibility gene of mammary tumors, at least partly, by activating a group of target genes, including Maspin and Gadd45alpha.

Characterization of frequently deleted 6q locus in prostate cancer

The long arm of chromosome 6 is frequently deleted in diverse human neoplasms. Our previous study showed a minimum deletion region between markers D6S1056 and D6S300 on chromosome 6q in primary prostate cancer (CaP). In this study, we further refined a 200-kb minimal region of deletion (6qTSG1) centered around D6S1013 marker. The 6qTSG1 transcripts contained complex multiple splicing variants with low or absent expression in CaP cells. None of the transcripts identified contained open reading frames that code for a protein in the NCBI database. The expression of 6qTSG transcripts revealed interesting hormonal regulation relevant to CaP biology. Expression of 6q TSG transcript was induced in LNCaP cells that were cultured in charcoal-stripped serum medium suggesting an upregulation of 6qTSG transcript by androgen ablation and cell growth inhibition/apoptosis. Induction of 6qTSG1 expression in response to androgen ablation was abrogated in androgen-independent derivatives of LNCaP cells. In summary, we have defined a candidate CaP suppressor locus on chromosome 6q16.1, and deletions of this locus are frequently associated with prostate tumorigenesis. In the light of emerging role of noncoding RNAs in cancer biology including CaP, future investigations of 6qTSG11 locus is warranted.

Angiotensinogen impairs angiogenesis in the chick chorioallantoic membrane

Angiotensinogen shares with other members of the serine protease inhibitor (serpin) family antiangiogenic properties. Angiotensinogen inhibits in vitro endothelial cell proliferation, and is antiangiogenic in ovo in the chick chorioallantoic membrane assay. The cellular mode of action of angiotensinogen has been studied by applying purified human angiotensinogen or Chinese hamster ovary cells producing recombinant angiotensinogen onto the developing chorioallantoic membrane. Vessel density of the control and angiotensinogen-treated areas was quantitated by using Sambucus nigra lectin, a specific endothelial cell marker. After 48 h of angiotensinogen treatment by either applying purified angiotensinogen or angiotensinogen-producing Chinese hamster ovary cells, there was a 70% decrease in mesodermic vessel density in comparison to the control sections. Angiotensinogen treatment induced a strong decrease in endothelial cell proliferation of the chorioallantoic membrane vasculature, as shown by incorporation of bromo-deoxyuridine. Two days after local angiotensinogen treatment, increased apoptosis of endothelial cells of mesodermal blood vessels was detected by transferase-mediated deoxyuridine triphosphate nick end labeling assay. As assessed by in situ hybridization, the gene expression pattern of the main vascular growth factors and their receptors was not altered by angiotensinogen. Angiotensinogen, therefore, impairs angiogenesis without altering the expression level of vascular growth factors through the induction of apoptosis and decreased endothelial cell proliferation.

Maspin: the new frontier

Maspin (mammary serine protease inhibitor) was identified in 1994 by subtractive hybridization analysis of normal mammary tissue and breast cancer cell lines. Subsequently, emerging evidence portrays maspin as a multifaceted protein, interacting with diverse group of intercellular and extracellular proteins, regulating cell adhesion, motility, apoptosis, and angiogenesis and critically involved in mammary gland development. The tissue-specific expression of maspin is epigenetically controlled, and aberrant methylation of maspin promoter is closely associated with maspin gene silencing. Identification of new tissue sites expressing maspin and novel maspin-binding partners has expanded the horizon for maspin research and promises maspin-based therapeutic approaches for combating cancer. This perspective briefly outlines the past and present strides in deciphering this unique molecule and speculates on new frontiers in maspin research and prospects of maspin as a diagnostic/prognostic indicator in cancer.

Cancer gene therapy targeting angiogenesis: An updated Review

Since the relationship between angiogenesis and tumor growth was established by Folkman in 1971, scientists have made efforts exploring the possibilities in treating cancer by targeting angiogenesis. Inhibition of angiogenesis growth factors and administration of angiogenesis inhibitors are the basics of anti-angiogenesis therapy. Transfer of anti-angiogenesis genes has received attention recently not only because of the advancement of recombinant vectors, but also because of the localized and sustained expression of therapeutic gene product inside the tumor after gene transfer. This review provides the up-to-date information about the strategies and the vectors studied in the field of anti-angiogenesis cancer gene therapy.